On 10/03/2017 12:23 AM, Jeff Law wrote: > On 09/20/2017 12:04 PM, Martin Sebor wrote: >> On 09/19/2017 03:00 PM, Joseph Myers wrote: >>> On Tue, 19 Sep 2017, Martin Sebor wrote: >>> >>>>> In general, the data structures where you need to ensure manually that if >>>>> >>>>> attribute A is listed in EXCL for B, then attribute B is also listed in >>>>> EXCL for A, seem concerning. I'd expect either data structures that make >>>>> >>>>> such asymmetry impossible, or a self-test that verifies that the tables in >>>>> >>>>> use are in fact symmetric (unless there is some reason the symmetry is not >>>>> >>>>> in fact required and symmetric diagnostics still result from asymmetric >>>>> tables - in which case the various combinations and orderings of >>>>> gnu_inline and noinline definitely need tests to show that the diagnostics >>>>> >>>>> work). >>>> >>>> If I understand correctly what you're concerned about then I don't >>>> think there are any such cases in the updated version of the patch. >>> >>> I don't see how you ensure that it's not possible to have such asymmetry. >>> My point wasn't so much "there was a bug in the previous patch version" as >>> >>> "the choice of data structures for defining such exclusions is prone to >>> such bugs". Which can be addressed either by using different data >>> structures (e.g. listing incompatible pairs in a single array) or by a >>> self-test to verify symmetry so a compiler with asymmetry doesn't build. >> >> Okay, that's a useful thing to add. It exposed a couple of missing >> attribute exclusions that I had overlooked. Thanks for the suggestion! >> Attached is an incremental diff with just these changes to make review >> easier and an updated patch. >> >> As an aside, there are a number of other possible logic errors in >> the attribute specifications that could be detected by self-tests. >> The one I ran into is misspelled attribute names. The added test >> detects misspelled names in exclusions, but not in the main specs. >> >> Martin >> >> gcc-81544-1-inc.diff >> >> > > >> gcc-81544-1.diff >> >> >> PR c/81544 - attribute noreturn and warn_unused_result on the same function >> accepted >> >> gcc/c/ChangeLog: >> >> PR c/81544 >> * c-decl.c (c_decl_attributes): Look up existing declaration and >> pass it to decl_attributes. >> >> gcc/c-family/ChangeLog: >> >> PR c/81544 >> * c-attribs.c (attr_aligned_exclusions): New array. >> (attr_alloc_exclusions, attr_cold_hot_exclusions): Same. >> (attr_common_exclusions, attr_const_pure_exclusions): Same. >> (attr_gnu_inline_exclusions, attr_inline_exclusions): Same. >> (attr_noreturn_exclusions, attr_returns_twice_exclusions): Same. >> (attr_warn_unused_result_exclusions): Same. >> (handle_hot_attribute, handle_cold_attribute): Simplify. >> (handle_const_attribute): Warn on function returning void. >> (handle_pure_attribute): Same. >> * c-warn.c (diagnose_mismatched_attributes): Simplify. >> >> gcc/ChangeLog: >> >> PR c/81544 >> * attribs.c (empty_attribute_table): Initialize new member of >> struct attribute_spec. >> (decl_attributes): Add argument. Handle mutually exclusive >> combinations of attributes. >> * attribs.h (decl_attributes): Add default argument. >> * selftest.h (attribute_c_tests): Declare. >> * selftest-run-tests.c (selftest::run_tests): Call attribute_c_tests. >> * tree-core.h (attribute_spec::exclusions, exclude): New type and >> member. >> * doc/extend.texi (Common Function Attributes): Update const and pure. >> >> gcc/testsuite/ChangeLog: >> >> PR c/81544 >> * c-c++-common/Wattributes-2.c: New test. >> * c-c++-common/Wattributes.c: New test. >> * c-c++-common/attributes-3.c: Adjust. >> * gcc.dg/attr-noinline.c: Adjust. >> * gcc.dg/pr44964.c: Same. >> * gcc.dg/torture/pr42363.c: Same. >> * gcc.dg/tree-ssa/ssa-ccp-2.c: Same. > OK. > jeff >
On targets enforcing a function alignment bigger than 4 bytes this triggers an error instead: +inline int ATTR ((aligned (4))) +finline_hot_noret_align (int); /* { dg-warning "ignoring attribute .aligned \\(4\\). because it conflicts with attribute .aligned \\(8\\)." } */ gcc/gcc/testsuite/c-c++-common/Wattributes.c:404:1: error: alignment for 'finline_hot_noret_align' must be at least 8^M